Modern aerospace structures are susceptible to mechanical surface damage. For example, hailstorms can damage an aircraft's fuselage, wings, or other structures while the aircraft is in flight or on the ground. Similarly, incidental contact with various ground objects can mechanically damage the surface of one or more structures of an aircraft or other type of aerospace structure. After the surface of one of an aircraft's structures is damaged, an inspector must evaluate any damage such as depressions including “dents” on the surface to determine whether the structure conforms to a manufacturer's or regulator's requirements. This process may involve measuring the depth or width of each dent and then dispositioning each dent as having an acceptable or unacceptable profile. In some cases, if a dent is sufficiently large or deep, repairs may need to be made.
Various approaches to measuring the depth or width of a surface dent on an aerospace structure exist. According to one approach, an inspector manually measures the depth and width of dents using a scale and a dial indicator gauge. Other approaches make use of laser line gauges or laser profilometry systems. Further, other approaches use interferometric devices that operate based on the moiré effect.